Research articles

Spin caloritronics exploits the effect of temperature on spin currents with a focus on features such as spin dependent thermal conductance, which are ideally suited for next generation spintronic devices. Here, the authors theoretically investigate a cold atom simulator of spin caloritronics comprising a one-dimensional spin chain between two temperature reservoirs and consider the dynamics of a spin impurity (spin flip) introduced into the chain.

When watching a movie of a physical process, one can conjecture whether it is running forward or backward in time by examining key physical parameters in the process. Here, the authors show that superpositions of (thermodynamic) quantum processes with opposite time’s arrows are also physically possible and observable, and explore the thermodynamic role played by the interference term.

Relativistic quantum mechanics is typically used to describe phenomena of high-energy physics but can also be applied to describe some features of quantum materials. Here, the authors use electrical circuits to simulate Dirac-like phenomena and measure Zitterbewegung and Klein tunneling for a one dimensional Bose-Hubbard model.

The study of high-order networks as attracted significant attention recently. The authors introduce the concept of computability for searching maximum clique in large networks and an optimized algorithm for finding cavities with different orders.

Subjecting materials to strong, carefully tuned light pulses are an increasingly popular route to realise novel physics and functionalities for solid-state systems, with one such example being Floquet engineering. Here, the authors propose to employ optical longitudinal conductivity to probe Floquet-Bloch bands, and demonstrate optical controllability of the conductivity of graphene.

Unidirectional spin Hall magnetoresistance (USMR) is a directionally dependent feature of a ferromagnetic/normal metal bilayer for which the underlying mechanisms are still under debate. Here, the authors investigate the crystallographic dependence of USMR in epitaxial Cr/Fe bilayers finding that electron-magnon scattering plays an important role.

Problem decomposition methods may help to overcome the size limitations of quantum hardware and allow largescale electronic structure simulations. Here, a method to simulate a ten-atom Hydrogen ring by decomposing it into smaller fragments that are amenable to a currently available trapped ion quantum computer is demonstrated experimentally.

The need for reduced dimensions of future devices pushes the limits of essential Si-based components and so alternative materials, such as carbon nanotubes or graphene, are being investigated as alternatives, but with new materials come new challenges. Here, the authors experimentally and theoretically investigate the on-currents for all-carbon transistors finding that contact spacing and length plays an important role in device performance.

Floquet-Bloch lattices are systems that are relatively difficult to implement in solid-state physics. Here, using a photonic lattice as an alternative, the authors experimentally observe Floquet-Bloch bands using a single-shot method which allows them to fully characterise the lattice eigenmode structure.

Spatial photonic Ising machines (SPIMs), a variant of optical Ising machines, are promising for large-scale problems but have limitations on the type of problems that can be mapped on them. Here, a variant of SPIMs is demonstrated that can realize anti-ferromagnetic Ising problems with some further experimental simplifications that have potentials for future large-scale Ising machines.

By exploiting the geometric frustration of a kagome crystal lattice, it is possible to enhance electron localisation and engineer exotic electronic structures such as electronic flat bands. Here, the authors use inelastic neutron scattering to investigate the evolution of spin excitations modes for FeSn and CoSn, finding that an anomalous flat mode actually arises from the material used to fix the sample to the aluminium holder for analysis instead of the expected magnetic flat bands.

In topological condensed-matter systems, axion insulators are elusive excitation and active research in running to spot their signature. In this work, the authors theoretically propose a picture to characterize the surface of axion insulators and a possible detection scheme for thermal transport experiments with a precisely half-quantized outcome.

Semiconductor research is undergoing transformative changes thanks to the discovery and development of novel materials. The authors disclose the role of electron-phonon interaction and impurity scattering in a novel ultrawide bandgap perovskite oxide, paving the way for new applications in high-power electronics.

Cell size fluctuations in stable environments are thought to be governed by simple scaling laws. However, the effect of time dependent conditions such as cell cycle on determining size distribution changes is less known. The authors use a new microfluidic device to demonstrate that scale invariance is maintained in E. coli’s response to abrupt starvation.

Current rectification in the THz regime using geometric diodes has been explained previously by exotic transport properties. Here, an alternative mechanism based on asymmetric bias-induced barrier lowering is presented.

Mechanical forces play important roles in cell biology and traction force microscopy (TFM) experiments have enabled quantification of the cell-generated forces when placed on substrates of distinct stiffnesses. Here the authors evaluate the effect of the Poisson’s ratio- one of the main descriptors of the material’s mechanical behaviour together with the Elastic Modulus, in the context of TFM experiments.

To increase the output intensity of conventional THz harmonic generation platforms, the medium is normally made continuously thicker. Here, 3D Dirac semimetal films are predicted to increase the THz output by orders of magnitude, but only up to an optimal thickness dictated by its nonlinear response.

A common problem in reconstructing weighted networks to represent real-world systems is that low-weight edges might appear due to noise, affecting the topology of the inferred network. Here, the authors propose a method based on persistent homology that allows one to investigate the higher-order network organization that can be created by low-weight, noisy edges.

Manipulation of the magnetization is of major importance in spintronics. The authors demonstrate that an electric field triggers a transverse flow of orbital moment: the so-called orbital Hall effect. This enables the efficient magnetization control, holding the promise for fast and miniaturized memories and sensors.

Understanding the motion of finite-sized particles in crowded environments is at the heart of important biological and physiological problems. Here, the authors construct a network-based mathematical framework for studying transport of macromolecules within crowded heterogeneous environments, such as the intracellular environment, and probe the interconnection of crowding and geometry upon macromolecular transport.